Low-temperature thermal reduction of suspended graphene oxide film for electrical sensing of DNA-hybridization

•Preparation of an electro-mechanical biosensor while a suspended GO membrane acted as a movable gate;•A low temperature thermal reduction approach of suspended GO film;•The resonance frequency of the electro-mechanical biosensor shifted with the graphene-biomolecule interaction;•The hybridization of a single stranded DNA was real-time detected in solution with the concentration limit of about 50 nM;

A reduced graphene oxide (RGO) based capacitive real time bio-sensor was presented. Suspended graphene oxide (GO) film was assembled electrophoretically between the source and drain electrodes of a transistor and then reduced by annealing in hydrogen/nitrogen forming gas to optimize the surface functional groups and conductivity. The resonance frequency of the transmission coefficient (S21) of the transistor was observed to shift with deoxyribonucleic acid (DNA)-hybridization, with a detecting limit of ~ 5 nM. The advantages of the bio-sensing approach include low-noise frequency output, solution based real time detection and capable of on-chip integration.